In recent years, a brushing method has been developed which makes it possible [a] to prevent alveolar pyorrhea, [b] to stop the progression of alveolar pyorrhea, or [c] to regenerate alveolar bone which has already been dissolved as a result of alveolar pyorrhea, by brushing vigorously for a long period of time with the bristle tips of the toothbrush inserted into the gingival sulcus (reference: Tsuneo Katayama, "Shiso Noro" ["Alveolar Pyorrhea"], Asahi Shinbunsha). FIG. 4(a) is a sectional view of a tooth sustaining alveolar pyorrhea, and FIG. 4(b) is a sectional view of a normal tooth. Even in the case of a healthy tooth, there is a gingival sulcus C with a depth of approximately 1 to 2 mm between the tooth A and the gingiva B. If bacteria multiply inside this gingival sulcus C, plaque consisting of said bacteria and their waste products will accumulate so that the gingival sulcus C eventually becomes blocked. As a result, air cannot reach inside of the gingival sulcus, and this leads to the multiplication of anaerobic bacteria which cause alveolar pyorrhea. These organisms invade the area between the gingiva B and the tooth root A2, and thus cause an inflammation. This inflammation is alveolar pyorrhea; when such alveolar pyorrhea occurs, pockets D are formed inside the gingival sulcus C, and the alveolar bone E which supports the tooth root A2 gradually dissolves.
Places from which it is especially difficult to remove plaque include the interdental gingival sulcus C and pockets D formed inside the gingival sulcus C. It is extremely difficult for the bristle tips of conventional toothbrushes to reach these areas. Accordingly, in the new brushing method mentioned above, a toothbrush in which bundles of stiff bristles are implanted in a single row is used. This toothbrush is pressed against the designated area, and a single bundle of stiff bristles is inserted into the gingival sulcus. The toothbrush is then caused to vibrate with a fine vibratory action while the bristle tips are allowed to rest in the aforementioned position. In this way, the bristle tips can reach the inside of the gingival sulcus C and the inside areas of the aforementioned pockets D, which could not be reached in the case of conventional toothbrushes because of interference by other bristles. Thus, by agitating the accumulated viscous plaque (which does not readily dissolve in water) with the bristle tips, it is possible to supply oxygen to the anaerobic bacteria which cause alveolar pyorrhea, thereby killing said bacteria.
However, in the case of the abovementioned brushing method, a special toothbrush with a small number of stiff bristles is used, and brushing is performed vigorously in each individual location without altering the position of the bristle tips. Furthermore, the patient is required to perform brushing for a long period of time, i.e., 1 to 3 hours per day. As a result, the patient's arm becomes tired, and the treatment requires an excessive amount of time, so that it is not easy to continue this treatment on a long-term basis.
Furthermore, although an electrically driven toothbrush may be used in order to shorten the brushing time, conventional electric toothbrushes are designed so that the bristles are caused to move in the lateral direction rather than in the longitudinal direction. Accordingly, the bristle bundles are bent so that the bristle tips constantly move in a direction which causes said bristle tips to be withdrawn. As a result, it is absolutely impossible to insert the bristle tips into the interdental gingival sulcus C or into the aforementioned pockets D as described above. It would also be conceivable to use an oral cavity cleaning device employing a jet water current in order to remove plaque from the gingival sulcus C or pockets D. However, as was described above, this plaque will not dissolve in water, and has a strong gumminess which causes said plaque to adhere firmly to the surfaces of the teeth. Accordingly, it is difficult to strip this plaque away using only the jet water current of an oral cavity cleaning device.